Disclaimer: this example was playing at beginner level or I wouldn't have been so far ahead.
In a recent game one of the beat up majors started coming to me for assistence. I was far, far ahead in military and the game was not in doubt so I decided to see if I could turn their fortunes around. I gave them 3 fast powerful ships that were at least 3 levels above what anyone else had.
One of the ships was used to win a couple of battles and then squandered the ship on a hopeless attack against a fortified starbase when it's hitpoints were almost exhausted.
The other two ships were parked and never used. I gave them another ship to replace the one that was destroyed and it was parked and never used.
The AI that I gave the ships to could have easily turned the game around with those ships but did not seem to have the heart to do it. Since the AI at higher difficulty seems to be based on other algorithms it might or might not make a difference.
This seems to be universal in all games involving AI. Once the AI decides it is beaten it is almost impossible to revive. I can remember in AOE, I would rush a team of workers over to enemy territory early and build a watch tower next to their town center. They might eventually destroy the tower but by that time they were so beaten up they never recovered and would just wander around aimlessly.
Of course this is about the beta and not the final.